I am looking to install a claw foot bathtub. Right now there is only a shower and sink. I can tie into either of these drains and supply lines but the sink is more convenient. The sink drain is 1.5". Will that work? Do I need a p-trap on the tub? Are there any potential problems? The sink is only about 3 feet from where the tub plumbing will be and the shower is about 7 feet. Thank you for your help!

Hi Bam...

A tub only requires an 1.5" drain pipe and vent so the 1.5" sink drain would be fine, but that 2" shower drain would be even better.

If you decide to go with the sink drain, you would cut a new wye fitting into the sink drain pipe and install a PTRAP under the tub waste and overflow assembly from the tub. You would need to add an 1.5" vent for the tub drain and connect that vent into the sink vent at a minimum of 42" off the finish floor (see image).

If the sink drain and vent are 2", by chance, then you could just connect into the sink drain and would not need to add vent for the tub... called WET VENTING. You would still need to add the PTRAP.

If you use the shower drain, again, you can probably use the shower vent to vent the tub if wet venting is allowed in your area... if not, you would need to add an 1.5" vent. You would still need to add the PTRAP, too.

Questions? Let us know...

Mark

Thanks Mark. I guess I have to use the shower drain since I need a p-trap and I have no desire to dig up a bunch of concrete. The shower is sunken (2 steps down) so I think I can install the trap, tie into the drain then fill the area with concrete or? I will still have to trench the concrete a bit but not too much. The new shower will then be only 1 step down. I planned on redoing the shower completely anyway so I think this should work well.

Is wet venting allowed in your area? Is your shower vented? This is on a slab, Correct? Let me know, Tom

I don't know if wet venting is allowed. I believe the shower is vented. On the roof is a vent that appears to be for that. It is like a shower/tub combo that is all tile. I think it is called a European Tub?? Anyway, I think it is vented but not sure and yes this is on slab. The sunken shower/tub area creates a ledge that I can chip away at to allow room to slope to a trap and then slope to the existing 2" drain (which I will stub up about 6" to the new shower floor). If it sounds like I know what I'm doing, I don't so all help is greatly appreciated.


Any thoughts on what to use to fill in the existing shower and cover the new piping (where I tie the new tub into the existing shower drain)? I'm assuming concrete. I think it will be about 6" deep.